1. Field of Invention
The present invention relates to an electro-optical panel including a plurality of scanning lines, a plurality of data lines, and switching elements arranged in a matrix pattern corresponding to intersections of the scanning lines and the data lines, and relates to an image-signal supplying circuit used in the electro-optical panel.
2. Description of Related Art
A known liquid crystal device can include a liquid crystal panel serving as the main part. An active matrix liquid crystal panel includes an element substrate provided with switching elements, which are arranged corresponding to pixel electrodes arranged in a matrix pattern, an opposing substrate provided with a color filter and so on, and liquid crystal filled between the substrates. In this configuration, when a scanning signal is applied to a switching element through a scanning line, that switching element is brought into conduction. In this conduction state, when an image signal is applied to a pixel electrode through a data line, a predetermined charge is accumulated in a liquid crystal layer between the pixel electrode and an opposing electrode (common electrode).
Also, a scanning-line drive circuit that can select a scanning line and a data-line drive circuit that can supply an image signal to a data line may be provided on the element substrate of the liquid crystal panel. Further, instead of providing the data-line drive circuit on the element substrate, the following methods may be used. That is, a driver IC chip, which has been mounted on a film by using a tape automated bonding (TAB) technique, is electrically and mechanically connected through an anisotropic conductive film provided at a predetermined position of the element substrate. Alternatively, the driver IC chip itself is electrically and mechanically connected to a predetermined position of the element substrate through an anisotropic conductive film by using a chip on glass (COG) technique.
FIG. 10 is a block diagram showing a known liquid crystal panel. The liquid crystal panel shown in FIG. 10 includes an image-display region A provided with scanning lines 2 and data lines 3, a COG region B, and a scanning-line drive circuit. Data-line driver IC for driving the data lines are connected to the COG region B by using a COG technique.
In order to display an image in this type of liquid crystal panel, a data-line driver IC must be mounted. Therefore, this liquid crystal panel cannot be inspected for display defects before mounting the data-line driver IC. When the inspection is performed after mounting the data-line driver IC, the entire liquid crystal panel is determined to be defective if the data-line driver IC has a problem, even if the liquid crystal panel without the data-line driver IC is acceptable. As a result, the cost for manufacturing the liquid crystal panel can increase.
The inspection can be performed by providing a pad on each data line and by supplying a signal to the pad through a probe. In this method, however, many pads are necessary if the pitch of the pixels of the liquid crystal panel is small. Accordingly, it is difficult to provide the pads, which is the mechanical limit. In particular, this is a serious problem in a high-definition liquid crystal panel.